单项选择题
普朗克定律(Planck’s distribution law)描述的是()。
A.黑体发射力(Total,hemispherical blackbody emissive power)
B.黑体光谱半球发射力(Spectral,hemispherical blackbody emissive power)
C.黑体光谱定向发射力(Spectral,hemispherical blackbody emissive power)
D.光谱辐射强度(Spectral Intensity of the emitted radiation)